scholarly journals Analysis of Cognitive Radio Spectrum Access with Optimal Channel Reservation

2007 ◽  
Vol 11 (4) ◽  
pp. 304-306 ◽  
Author(s):  
Xiaorong Zhu ◽  
Lianfeng Shen ◽  
Tak-shing Yum
Keyword(s):  
Cognitive Radio ◽  
Radio Spectrum ◽  
Spectrum Access ◽  
Channel Reservation

The Impact of Regulations on the Business Case for Cognitive Radio

2013 ◽  
pp. 142-170
Author(s):  
Peter Anker
Keyword(s):  
Cognitive Radio ◽  
Potential Application ◽  
Business Case ◽  
Radio Spectrum ◽  
Considerable Degree ◽  
Regulatory Regime ◽  
Spectrum Access ◽  
The Impact

Cognitive Radio holds an interesting promise for improved utilisation of the radio spectrum. However, there is a considerable degree of uncertainty regarding the potential application of cognitive radio. One of the reasons for this uncertainty is the need for changes in the regulatory regime to allow for more dynamic forms of spectrum access. In addressing the necessary changes in regulations, the regulator should be well aware of the perspective of the entrepreneur. Eventually, it is the entrepreneur who invests in CR technology and thereby realises the goal of improved utilisation of the radio spectrum. This chapter addresses the impact on the business case for cognitive technologies of the regulatory regime and the choices on the fundamental CR technology that regulators will have to make.

scholarly journals Capacity optimization for radio resource allocation in cognitive networks

2021 ◽  
Author(s):  
Mohamed Elalem
Keyword(s):  
Cognitive Radio ◽  
Spectrum Sharing ◽  
Cognitive Radio Network ◽  
Radio Spectrum ◽  
Opportunistic Spectrum Access ◽  
Effective Capacity ◽  
Radio Network ◽  
Spectrum Access ◽  
Primary Users ◽  
Access Model

With the rapid development of wireless services and applications, the currently radio spectrum is becoming more crowded. How to accommodate more wireless services and applications within the limited radio spectrum becomes a big challenge faced by modern society. Cognitive radio (CR) is proposed as a promising technology to tackle this challenge by introducing secondary users (SUs) to opportunistically or concurrently access the spectrum allocated to primary users (PUs). Currently, there are two prevalent CR models: the spectrum sharing model and the opportunistic spectrum access model. In the spectrum sharing model, the SUs are allowed to coexist with the PUs as long as the interferences from SUs do not degrade the quality of service (QoS) of PUs to an unacceptable level. In the opportunistic spectrum access model, SUs are allowed to access the spectrum only if the PUs are detected to be inactive. These two models known as underlay and overlay schemes, respectively. This thesis studies a number of topics in CR networks under the framework of these two schemes. First, studied cognitive radio transmissions under QoS delay constraints. Initially, we focused on the concept: effective capacity for cognitive radio channels in order to identify the performance in the presence of QoS constraints. Both underlay and overlay schemes are studied taking into consideration the activity of primary users, and assuming the general case of channel fading as Gamma distribution. For this setting, we further proposed a selection criterion by which the cognitive radio network can choose the adequate mode of operation. Then, we studied the cognitive radio transmissions focusing on Rayleigh fading channel and assumed that no prior channel knowledge is available at the transmitter and the receiver. We investigated the performance of pilot-assisted transmission strategies. In particular, we analyzed the channel estimation using minimum mean-square-error (MMSE) estimation, and analyzed efficient resource allocation strategies. In both cases, power allocations and effective capacity optimization were obtained. Effective capacity and interference constraint were analyzed in both single-band and multi-band spectrum sensing settings. Finally, we studied optimal access probabilities for cognitive radio network using Markov model to achieve maximum throughput for both CR schemes.

Cross-Layer Design in Cognitive Radio Networks

2012 ◽  
pp. 282-310 ◽  
Author(s):  
Bin Wang ◽  
Zhiqiang Wu ◽  
Zhongmei Yao
Keyword(s):  
Cognitive Radio ◽  
Cognitive Radio Networks ◽  
Dynamic Spectrum Access ◽  
Radio Spectrum ◽  
Radio Networks ◽  
Opportunistic Spectrum Access ◽  
Future Research ◽  
Cross Layer ◽  
Spectrum Access ◽  
Frequency Bands

Radio spectrum has become a precious resource. Most frequency bands have been allocated for exclusive use in the US. However, studies have shown that a very large portion of the radio spectrum is unused or underused for long periods of time at a given geographic location. Therefore, allowing users without a license to operate in licensed bands while causing no interference to the license holder becomes a promising way to satisfy the fast growing need for spectrum resources. Dynamic spectrum access and cognitive radio are technologies for enabling opportunistic spectrum access and enhancing the efficiency and utilization of the spectrum. A cognitive radio adapts to the environment in which it operates by sensing the spectrum and then opportunistically exploiting unused and/or underused frequency bands in order to achieve certain performance goals. Due to the close coupling and interaction among protocol layers, the optimal design of opportunistic spectrum access and cognitive radio networks calls for a cross-layer approach that integrates signal processing and networking with regulatory policy making. This chapter introduces basic concepts, design issues involved, and some recent development in this emerging technological field. Future research directions are also briefly examined.

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